The present invention relates to a molding machine in general, and more particularly to a plasticizing and injecting device for use in an injection molding machine.
There are already known various constructions of injection molding machines which, generally speaking, include a mold consisting of two mold halves, a plasticizing and injecting arrangement mounted on a support for displacement toward and away from the mold, an arrangement for feeding synthetic plastic material granulate into the plasticizing and injecting arrangement, and a drive for the plasticizing and injecting arrangement. The present invention will now be explained as utilized in one particular type of an injection molding machine, but it is to be understood that the basic concept of the present invention can also be utilized in other types of injection molding machines.
The particular injection molding machine with which the present invention is concerned includes a support and a plurality of beams on which different parts of the machine are mounted for displacement relative to one another. The plasticizing and injecting arrangement of this particular machine includes a feed screw which is mounted in a housing for rotation about an axis of an input shaft, and also for axial displacement relative to the housing.
This type of an injection molding machine further includes a stationary platen and another platen which is mounted for displacement toward and away from the stationary platen. The two platens have support surfaces which face one another, and the two mold sections are connected to the support surfaces of the platens in alignment with one another. When this conventional injection molding machine is to be operated, the mold is closed by displacing the two platens toward one another so that the two mold sections form a mold, and the plasticized synthetic plastic material is injected into the interior of the mold through an inlet opening which passes through the stationary platen and through the mold section connected thereto. The plasticizing and injecting arrangement is mounted on the abovementioned beams at the side of the stationary platen which faces away from the mold and includes, in general, a plasticizing and injecting cylinder housing which is mounted on a support, and a plasticizing and injecting screw located in the interior of the housing. The housing has an inlet opening, and a funnel communicates with the inlet opening of the housing and serves the purpose of storing and conveying synthetic plastic material in form of granulate into the interior of the cylinder housing. Prior to injecting the synthetic plastic material, it must be plasticized, which is done in a conventional manner by rotating the plasticizing and injecting screw by energizing a drive for the screw. The granulated synthetic plastic material is engaged by the rotating screw and is transported in direction toward an outlet nozzle mounted at the end of the housing which faces toward the stationary platen. Simultaneously therewith, the feed screw conducts a movement in the axial direction thereof away from the stationary platen. When the material in the cylinder housing is plasticized in a conventional manner, the plasticizing and injecting screw is displaced axially in direction toward the stationary platen, so that the plasticized synthetic plastic material exits from the interior of the housing into the interior of the mold through the nozzle of the housing and the inlet opening of the mold. The above arrangement is fully conventional and has been described only to an extent necessary for understanding the present invention and the environment in which it is used.
Occasionally, the plasticizing and injecting screw must be either replaced or cleaned, so that access must be obtained to the interior of the housing from one of the ends thereof. In one known injection molding machine of the type here under consideration, the entire injection arrangement is mounted on the aforementioned beams for displacement relative thereto by means of so-called driving cylinders, in such a manner that the injection assembly can be laterally pivoted as soon as the nozzle disengages the stationary platen. This enables the operating personnel to gain access to the end of the injection assembly at which the nozzle is mounted, so that that part of the housing which carries the nozzle can be disassembled from the remainder of the housing so that the screw can be cleaned or removed from the housing. However, experience with this type of an apparatus has shown that such a disassembling operation is very time-consuming and laborious. In addition thereto, when the screw is either cleaned or replaced, and the housing reassembled, the position of the nozzle must always be adjusted in order to properly cooperate with the inlet opening of the mold. A further disadvantage of this arrangement is that the injection assembly must be pivoted in the lateral direction to such an extent until the end of the housing which carries the nozzle fully clears the stationary platen so as to enable the operating personnel to disassemble the housing without being hindered by the presence of the stationary platen during the disassembling operation. This, of course, makes the injecting assembly and thus the entire injection molding machine rather expensive.